Electronic apparatus and method of controlling power supply

ABSTRACT

[Object] To effectively reduce power consumption of a wearable optical device by determining whether the wearable optical device is usable. [Solution] Provided is an electronic apparatus including a wearable optical device, a state detection unit configured to detect a state relating to the wearable optical device, a state determination unit configured to determine that the detected state is at least one of a first state in which the wearable optical device is worn by a user in usable state or a second state in which the wearable optical device is worn or carried by the user in unusable state, and a power supply controller configured to control a power supply state of the electronic apparatus based on a result obtained by the determination.

TECHNICAL FIELD

The present disclosure relates to an electronic apparatus and a methodof controlling power supply.

BACKGROUND ART

A various types of optical devices allowing a viewer to perceive avirtual image superimposed on an image in real space have been recentlydeveloped. An example of such optical devices includes a wearableoptical device, and in particular, a device that is worn by the user onthe head is known as a head-mounted display (HMD). An exemplary type ofthe HMD is known in which a half mirror serving as a display surface isprovided in front of the viewer's pupils and an image (real image) isformed on the display surface. Another type of the HMD is developed inwhich guidance of image display light to the viewer's pupils using anoptical system allows the viewer to perceive an image (virtual image).As one example, Patent Literature 1 discloses the technique thatimplements an HMD capable of guiding the image display light in thelateral direction with respect to the viewer's pupils to be incident onthe viewer's pupils.

For example, the use of the technique disclosed in Patent Literature 1or other techniques becomes increasingly reducing in size and weight ofthe wearable optical device such as HMD. The continuous long-term usewithout frequent charging or the like is desirable due to thecharacteristics of wearable devices. Under such circumstances, varioustechniques for reduction in power consumption of the wearable opticaldevice have been developed. As one example, Patent Literature 2discloses a technique for reduction in power consumption of an HMD byshutting off the power when a sensor for detecting a movement determinesthat the HMD is not mounted and then by supplying again the power whenany movement is detected.

CITATION LIST Patent Literature

Patent Literature 1: JP 4776285B

Patent Literature 2: JP 3901061B

SUMMARY OF INVENTION Technical Problem

Although the technique disclosed in Patent Literature 2 as an examplecan reduce power consumption of the wearable optical device, this is notnecessarily a satisfactory solution. As one example, there may be astate in which a movement is not detected, that is, not only when theuser does not wear the HMD but also when the user wears or carries awearable optical device that is in unusable state. In this case, ifoperations including the generation of image light can be stopped, theeffect of reducing power consumption can be further improved. However,the technique as disclosed in Patent Literature 2 is difficult to detecta difference in attachment states of the wearable optical device asdescribed above.

Therefore, an embodiment of the present disclosure provides a novel andimproved electronic apparatus and method of controlling power supply,capable of effectively reducing power consumption of a wearable opticaldevice by determining whether the wearable optical device is usable.

Solution to Problem

According to the present disclosure, there is provided an electronicapparatus including a wearable optical device, a state detection unitconfigured to detect a state relating to the wearable optical device, astate determination unit configured to determine that the detected stateis at least one of a first state in which the wearable optical device isworn by a user in usable state or a second state in which the wearableoptical device is worn or carried by the user in unusable state, and apower supply controller configured to control a power supply state ofthe electronic apparatus based on a result obtained by thedetermination.

According to the present disclosure, there is provided a method ofcontrolling power supply including detecting a state relating to awearable optical device, determining that the detected state is at leastone of a first state in which the wearable optical device is worn by auser in usable state or a second state in which the wearable opticaldevice is worn or carried by the user in unusable state, and controllinga power supply state of an electronic apparatus including the wearableoptical device based on a result obtained by the determination.

It is possible to detect a state in which the wearable optical device isworn by the user in usable state and a state in which it is worn orcarried by the user in unusable state on the basis of informationindicating a state of the wearable optical device. Thus, not only whenthe wearable optical device is not worn by the user but also when it isworn or carried but is in unusable state, it is possible to change astate of power supply of the electronic apparatus including the wearableoptical device, thereby reducing the power consumption effectively.

Advantageous Effects of Invention

According to the embodiments of the present disclosure, the powerconsumption of the wearable optical device can be reduced effectively bydetermining whether the wearable optical device is usable.

Note that the effects described above are not necessarily limited, andalong with or instead of the effects, any advantageous effect set forthherein or other effects that can be expected from the presentspecification may be exhibited.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing a schematic configuration of a systemaccording to a first embodiment of the present disclosure.

FIG. 2 is a block diagram showing a schematic functional configurationof the system shown in FIG. 1.

FIG. 3 is a diagram showing an example of the sequence of processes ofthe system according to the first embodiment of the present disclosure.

FIG. 4 is a block diagram showing a functional configuration forcontrolling power supply of an HMD in the first embodiment of thepresent disclosure.

FIG. 5 is a diagram showing the relationship between the detection axesof an acceleration sensor and the direction of a gravitationalacceleration component in the first embodiment of the presentdisclosure.

FIG. 6 is a flowchart showing an example of a detection process based onan acceleration detection value in the first embodiment of the presentdisclosure.

FIG. 7 is a flowchart showing an example of a detection process based onthe acceleration variation in the first embodiment of the presentdisclosure.

FIG. 8 is a diagram illustrated to describe a method of returning from apower saving state of a processor in the first embodiment of the presentdisclosure.

FIG. 9 is a schematic block diagram showing a functional configurationof a system according to a second embodiment of the present disclosure.

FIG. 10 is a diagram showing an example of a switch used to detect thestate of an attachment member in the second embodiment of the presentdisclosure.

FIG. 11 is a block diagram showing a functional configuration used forcontrolling power supply of an HMD in the second embodiment of thepresent disclosure.

FIG. 12 is a diagram showing an example of a switch used to detect astate of an attachment member in a modification of the second embodimentof the present disclosure.

FIG. 13 is a schematic block diagram showing a functional configurationof a system according to a third embodiment of the present disclosure.

FIG. 14 is a block diagram showing a functional configuration used forcontrolling power supply of the HMD in the third embodiment of thepresent disclosure

FIG. 15 is a flowchart showing an example of a process performed bycombining the attachment state detection in the first, second, and thirdembodiments of the present disclosure.

FIG. 16 is a block diagram showing an example of a hardwareconfiguration of an electronic apparatus according to an embodiment ofthe present disclosure.

DESCRIPTION OF EMBODIMENT(S)

Hereinafter, (a) preferred embodiment(s) of the present disclosure willbe described in detail with reference to the appended drawings. In thisspecification and the drawings, elements that have substantially thesame function and structure are denoted with the same reference signs,and repeated explanation is omitted.

The description will be given in the following order.

-   -   1. First Embodiment        -   1-1. System Configuration        -   1-2. Control of Power Supply of HMD    -   2. Second Embodiment    -   3. Third Embodiment    -   4. Other Examples    -   5. Hardware Configuration    -   6. Supplement

1. First Embodiment (1-1. System Configuration)

FIG. 1 is a diagram showing a schematic configuration of a systemaccording to a first embodiment of the present disclosure. FIG. 2 is ablock diagram showing a schematic functional configuration of the systemshown in FIG. 1. Referring to FIGS. 1 and 2, the system 10 includes ahead-mounted display (HMD) 100, a smartphone 200, and a server 300.Hereinbelow, configurations of the respective devices will be described.

(Head-Mounted Display)

The HMD 100 includes a display unit 110 and a control unit 160. Thedisplay unit 110 has a housing in the shape of, for example, glasses,and is worn by a user (observer) on his or her head. The control unit160 is connected to the display unit 110 by a cable.

The display unit 110 is provided with a light source 112 and a lightguide plate 114 as shown in FIG. 1. The light source 112 emits imagedisplay light according to control of the control unit 160. The lightguide plate 114 guides the image display light incident from the lightsource 112, and then emits the image display light to a positioncorresponding to the eyes of the user. The eyes of the user receiveincidence of light that is incident on the light guide plate 114 from areal space and is then transmitted through the light guide plate 114,and the image display light guided from the light source 112 by thelight guide plate 114. Accordingly, the user wearing the display unit110 can perceive an image being superimposed on the real space. Notethat, for the configuration for causing the image display light to beemitted from the light source 112 through the light guide plate 114, forexample, the technology disclosed in JP4776285B described above may beused. The display unit 110 may be further provided with an opticalsystem that is not illustrated for the configuration.

Further, the display unit 110 is provided with a motion sensor 116, anda camera 118 as shown in FIG. 2. The motion sensor 116 includes, forexample, a triaxial acceleration sensor, a triaxial gyro sensor, and atriaxial geomagnetic sensor. Based on acceleration, an angular velocity,and a direction of the display unit 110 detected by the sensors, anattitude and a motion (displacement and rotation) of the display unit110 can be specified. The camera 118 photographs images of the realspace. The images photographed by the camera 118 are treated as, forexample, images corresponding to the visual field of the user in thereal space.

The control unit 160 is provided with a processor 162, a memory 164, acommunication device 166, an input key 168, a touch sensor 170, amicrophone 172, a speaker 174, an acceleration sensor 176, and a battery178. The processor 162 operates according to programs stored in thememory 164 to provide various functions. The function of a statedetermination unit, a power supply controller, or the like, which willbe described later, is implemented by the processor 162, as one example.The processor 162 transmits control signals to the display unit 110 inwired communication through a cable, and provides power for the lightsource 112 and the motion sensor 116. In addition, the processor 162acquires data output from the motion sensor 116 and the camera 118provided in the display unit 110, and executes processes based on thedata.

The memory 164 stores various kinds of data for operations of theprocessor 162. For example, the memory 164 stores programs for theprocessor 162 to realize various functions. In addition, the memory 164temporarily stores data output from the motion sensor 116 and the camera118 of the display unit 110. The communication device 166 executeswireless communication with the smartphone 200. For the wirelesscommunication, for example, Bluetooth (a registered trademark), Wi-Fi,or the like is used. The input key 168 includes, for example, a returnkey, a Push-to-Talk (PTT) key, and the like, and acquires useroperations with respect to the HMD 100. The touch sensor 170 likewiseacquires user operations with respect to the HMD 100. To be morespecific, the touch sensor 170 acquires, for example, operations such astapping, swiping and the like performed by a user.

The microphone 172 converts sound into an audio signal and provides itto the processor 162. The speaker 174 outputs sound under control of theprocessor 162. The acceleration sensor 176 is a three-axis accelerationsensor as one example, and detects acceleration of the control unit 160.The battery 178 supplies power to the entire components of the controlunit 160 and the display unit 110. The power supply from the battery 178is controlled depending on the state of power supply that is set by theprocessor 162, as one example.

Note that a small size and light weight of the display unit 110 areintended in the HMD 100 such that the processor 162, the microphone 172,the speaker 174, the battery 178, and the like can be mounted in thecontrol unit 160, and the display unit 110 and the control unit 160 areseparated from each other, but connected with a cable. Since the controlunit 160 is also carried by a user, it is desirable that it be as smalland light as possible. Thus, by setting the functions realized by theprocessor 162 as minimum functions for controlling the display unit 110and other functions to be realized by the smartphone 200, for example, asmall size of the entire control unit 160 and battery 178 attributableto a reduction in power consumption of the processor 162 may also beattempted.

(Smartphone)

The smartphone 200 is provided with a processor 202, a memory 204,communication devices 206 and 208, a sensor 210, a display 212, a touchpanel 214, a Global Positioning System (GPS) receiver 216, a microphone218, a speaker 220, and a battery 222. The processor 202 realizesvarious functions as it operates according to programs stored in thememory 204. As described above, as the processor 202 realizes variousfunctions in cooperation with the processor 162 provided in the controlunit 160 of the HMD 100, the control unit 160 can be small and light.The memory 204 stores various kinds of data for operations of thesmartphone 200. For example, the memory 204 stores programs for theprocessor 202 to realize the various functions. In addition, the memory204 temporarily or permanently stores data acquired by the sensor 210and the GPS receiver 216 and data transmitted to and received from theHMD 100.

The communication device 206 executes wireless communication usingBluetooth (a registered trademark), Wi-Fi, or the like with thecommunication device 166 provided in the control unit 160 of the HMD100. In addition, the communication device 208 executes networkcommunication with the server 300. The network communication may beexecuted via, for example, a mobile telephone network. The display 212displays various images according to control of the processor 202. Thetouch panel 214 is disposed on the display 212, and acquires touchoperations of the user with respect to the display 212. The GPS receiver216 receives GPS signals for measuring latitude, longitude, and altitudeof the smartphone 200. The microphone 218 converts sounds into audiosignals, and then provides the signals to the processor 202. The speaker220 outputs sounds according to control of the processor 202. Thebattery 222 supplies power to the entire smartphone 200.

(Server)

The server 300 is provided with a processor 302, a memory 304, and acommunication device 306. Note that the server 300 is realized, forexample, through cooperation between a plurality of server devices on anetwork; however, it will be described as a virtual single device hereinfor simplification of description. The processor 302 realizes variousfunctions as it operates according to programs stored in the memory 304.The processor 302 of the server 300 executes various informationprocesses according to, for example, requests received from thesmartphone 200, and transmits results thereof to the smartphone 200. Thememory 304 stores various kinds of data for operations of the server300. For example, the memory 304 stores programs for the processor 302to realize the various functions. Further, the memory 304 maytemporarily or continuously store data uploaded from the smartphone 200.The communication device 306 executes network communication via, forexample, a mobile telephone network with the smartphone 200.

Hereinabove, the system configuration according to the first embodimentof the present disclosure has been described. Note that, in the presentembodiment, the HMD 100 is an example of an electronic apparatus,including the wearable optical device (display unit 110). As describedabove, the HMD 100 makes an observer perceive images by guiding imagedisplay light to the eyes of the observer using the light guide plate114. Thus, although the term “display” is used, the HMD 100 is notnecessarily a device that causes images to be formed on its displayplane. Of course, an HMD of another known type such as a type of HMD inwhich images are formed on its display plane may be used instead of theHMD 100.

In addition, the system configuration described above is an example, andvarious other system configurations are also possible. For example, theHMD 100 may not necessarily have the display unit 110 and the controlunit 160 separated from each other, and the entire configuration of theHMD 100 described above may be consolidated in a glasses-type housingsuch as the display unit 110. In addition, as described above, at leastsome of the functions for controlling the HMD 100 may be realized by thesmartphone 200. Alternatively, the display unit 110 may also be providedwith a processor and thus information processing of the HMD 100 may berealized in cooperation between the processor 162 of the control unit160 and the processor of the display unit 110.

As another modified example, the system 10 may not include thesmartphone 200, and communication may be directly executed between theHMD 100, and the server 300. In addition, in the system 10, thesmartphone 200 may be replaced by another device that can executecommunication with both of the HMD 100 and the server 300, for example,a tablet terminal, a personal computer, a portable game device, or thelike.

FIG. 3 is a diagram showing an example of the sequence of processes ofthe system according to the first embodiment of the present disclosure.Referring to FIG. 3, first, a user operation is input to the controlunit 160 of the HMD 100 via the touch sensor 170 (S101). At that time,the processor 162 transmits information indicating the content of theuser operation to the smartphone 200 using the communication device 166(S103). The processor 202 of the smartphone 200 determines the contentof an image to be displayed next based on the information from the HMD100 received through the communication device 206 (S105). Although notillustrated, the processor 202 may communicate with the server 300 atthat time using the communication device 208 to acquire informationnecessary for the image to be displayed next.

Next, the processor 202 transmits the information necessary for theimage to be displayed next, for example, an icon, text, or the like, tothe HMD 100 using the communication device 206 (S107). The processor 162of the HMD 100 generates the image to be displayed next (frame image)based on the information from the smartphone 200 received through thecommunication device 166 (S109). Further, the processor 162 controls thelight source 112 of the display unit 110 based on data of the generatedframe image, and thereby updates a frame of an image provided with imagedisplay light emitted from the light source 112 (S111).

(1-2. Control of Power Supply of HMD)

FIG. 4 is a block diagram showing a functional configuration forcontrolling power supply of an HMD in the first embodiment of thepresent disclosure. Referring to FIG. 4, the control of power supply ofthe HMD is implemented in the present embodiment by the functionalconfiguration that includes a state determination unit 510 and a powersupply controller 520.

As described above, in the system 10, these functional components areimplemented by allowing the processor 162 included in the control unit160 of the HMD 100 to be executed in accordance with the program storedin the memory 164. Alternatively, some or all of the functionalcomponents may be implemented by allowing the processor 202 of thesmartphone 200 communicating with the HMD through wireless communicationsuch as Bluetooth (registered trademark) and Wi-Fi to be executed inaccordance with the program stored in the memory 204. Similarly, some orall of the functional components may be implemented by allowing theprocessor 302 of the server 300 to be executed in accordance with theprogram stored in the memory 304. In other words, the functionalcomponents may be implemented in any electronic apparatus (HMD 100,smartphone 200, or server 300) included in the system 10 or may beimplemented by a plurality of electronic apparatuses included in thesystem 10 in cooperation with each other.

(State Determination)

The determination of a state of the display unit 110 of the HMD 100performed by the state determination unit 510 will be first described.In the present embodiment, the state determination unit 510 determinesthat a state of the attitude or movement of the display unit 110indicated by a detection value obtained by the acceleration sensorincluded in the motion sensor 116 is at least one of a first state and asecond state. The first state is a state in which the display unit 110is worn by the user in usable state. The second state is a state inwhich the display unit 110 is worn or carried by the user in unusablestate. The display unit 110 is an example of the wearable optical devicein the present embodiment.

More specifically, in the present embodiment, the state determinationunit 510 uses information indicating acceleration of the display unit110 as the information indicating the state of attitude or movement ofthe display unit 110. The information indicating acceleration isacquired by the acceleration sensor included in the motion sensor 116provided in the display unit 110. Thus, the motion sensor 116 is anexample of a state detection unit configured to detect the state of thewearable optical device in the present embodiment. The statedetermination unit 510 determines the state on the basis of a detectionvalue and/or acceleration variation of the display unit 110, as morespecifically described below.

(1) State Determination Using Acceleration Detection Value

When the three-axis acceleration sensor detects acceleration of thedisplay unit 110, the detected acceleration contains a gravitationalacceleration component (g≈9.8 m/s²). The gravitational accelerationcomponent has a fixed direction (vertically downward), and thus theattitude of the display unit 110 can be specified on the basis of therelative direction of the gravitational acceleration component withrespect to the detection axes (x-axis, y-axis, and z-axis) of thethree-axis acceleration sensor. This will be described in detail withreference to FIG. 5.

FIG. 5 is a diagram showing the relationship between the detection axes(x-axis, y-axis, and z-axis) of the three-axis acceleration sensorincluded in the display unit 110 and the direction of the gravitationalacceleration component G of acceleration. In the shown example, thedetection axes of the three-axis acceleration sensor are set on thebasis of the attitude of the display unit 110 shown in the portion (a)(the attitude when it is properly mounted on the user's head). Thedetection axis includes the x-axis in the front and rear direction(direction from rear to front is the positive direction), the y-axis inthe right and left direction (direction from right to left is thepositive direction), and the z-axis in the up and down direction(direction from down to up is the positive direction), as viewed fromthe user who wears the display unit 110. In the portion (a), thegravitational acceleration component G of acceleration is detected inthe negative direction of the z-axis.

In this description, when the display unit 110 is inclined from theattitude shown in the portion (a) to that shown in the portion (b) asone example, the absolute direction of the gravitational accelerationcomponent G is not changed, but the detection axes of the three-axisacceleration sensor are inclined. Thus, in the case of the portion (b),the gravitational acceleration component G of acceleration is detectedin an inclined direction intersecting the respective detection axes. Theinclined attitude of the display unit 110 as shown in the portion (b)may happen when the display unit 110 is raised from the front of theuser's eyes and is worn on the forehead or when the display unit 110 ishung around the user's neck, as one example.

Furthermore, when the display unit 110 is inverted from the attitudeshown in the portion (a) to that shown in the portion (c) as oneexample, the absolute direction of the gravitational accelerationcomponent G is not changed, but the detection axes of the three-axisacceleration sensor are reversed. In other words, the x-axis, they-axis, and the z-axis have the same direction as the portion (a), buttheir orientations are reversed from positive to negative or vice versa.Thus, in the portion (c), the gravitational acceleration component G ofacceleration is the positive direction of the z-axis, that is, it isdetected in the direction reversed from the case in the portion (a).

Unlike other mobile devices, the display unit 110 is mounted on aparticular part (e.g., head) of the user's body, and thus the attitudeduring use is substantially determined. More specifically, the displayunit 110 is typically used with the attitude shown in the portion (a).Thus, in the present embodiment, the state determination unit 510 iscapable of determining the state of the display unit 110 on the basis ofa change in detection values (vectors) of acceleration as shown in FIG.5.

More specifically, in the example shown in FIG. 5, when the direction ofthe gravitational acceleration component G contained in the accelerationdetection value corresponds to a predetermined direction (negativedirection of z-axis), the state determination unit 510 is capable ofdetecting a first state in which the display unit 110 is worn by theuser in usable state (the state shown in the portion (a)). When thedirection of the gravitational acceleration component G contained in theacceleration detection value differs from the predetermined direction(negative direction of z-axis), the state determination unit 510 iscapable of detecting a second state in which the display unit 110 isworn or carried by the user in unusable state (the state shown in theportions (b) and (c)). Examples of the second state may include a statein which the display unit 110 is placed on a table or the like withoutbeing worn or carried by the user. Such a state is also treated in a waysimilar to the state in which the display unit 110 is worn or carried bythe user in unusable state from a point of view that it is preferable tobe set as a power saving state by power supply control, which will bedescribed later.

Alternatively, in the example shown in FIG. 5, when the direction of thegravitational acceleration component G contained in the accelerationdetection value is the direction opposite (positive direction of z-axis)to a predetermined direction, the state determination unit 510 may beconfigured to detect the second state. In this case, unlike the aboveexample, the states shown in the portions (a) and (b) correspond to thefirst state, and the state shown in the portion (c) corresponds to thesecond state.

In this description, in the state shown in the portion (a), the displayunit 110 mounted on the user's head does not necessarily maintain ahorizontal level, but it has some degree of inclination with the head'smovement. Thus, the state shown in the portion (a) may be determined tobe not only a case where the gravitational acceleration component Gcorresponds to a predetermined direction (negative direction of z-axis)but also a case where it substantially corresponds to the predetermineddirection, that is, a case where a difference between the gravitationalacceleration component G and the predetermined direction is within anacceptable range.

Similarly, for example in the state shown in the portion (c), thedisplay unit 110 is estimated to be in the inverted state, but it is notstrictly maintained in the inverted attitude because it is not in usablestate. Thus, the state shown in the portion (c) may be determined to benot only a case where the gravitational acceleration component G is inthe direction opposite (negative direction of z-axis) to a predetermineddirection but also a case where the direction is substantially oppositeto the predetermined direction, that is, a case where a differencebetween the gravitational acceleration component G and a state of beingopposite to the predetermined direction is within an acceptable range.

As described above, in the example shown in FIG. 5, the display unit 110is typically used in the state shown in the portion (a). However, whenthe user's head inclines for a moment, the attitude of the display unit110 will be changed. On the other hand, it seldom occurs that the userkeeps his head inclined over a long time. In such a case, as describedbelow, the state determination unit 510 can execute the determinationperformed by combining the acceleration detection value with time,thereby detecting the state of the display unit 110 in a moreappropriate manner.

FIG. 6 is a flowchart showing an example of a process in the case wherethe state determination unit 510 executes the determination performed bycombining the acceleration detection value with time. Referring to FIG.6, the state determination unit 510 acquires an acceleration detectionvalue obtained by detecting acceleration of the display unit 110 (S201).In this connection, the acceleration detection value may be acquired bythe three-axis acceleration sensor included in the motion sensor 116.Then, the state determination unit 510 determines whether the directionof a gravitational acceleration component contained in the accelerationdetection value corresponds to a predetermined direction (S203). Thepredetermined direction is the negative direction of the z-axis in theexample shown in FIG. 5, as one example. As described above, thedetermination of direction may be performed while permitting adifference within a predetermined acceptable range.

If it is determined in step S203 that the direction of a gravitationalacceleration component contained in the acceleration detection valuecorresponds to the predetermined direction (YES), the process returns tostep S201. On the other hand, if it is not determined that the directionof a gravitational acceleration component contained in the accelerationdetection value corresponds to the predetermined direction (NO), thestate determination unit 510 may determine whether the direction of thegravitational acceleration component is the direction opposite to thepredetermined direction (S205). In the case where this determinationprocess is performed, if it is determined that the gravitationalacceleration component is in the direction opposite to the predetermineddirection (YES), a process of waiting for the lapse of a predeterminedtime in step S207 is not performed, and the state determination unit 510determines that the display unit 110 is in the second state in which thedisplay unit 110 is worn or carried by the user in unusable state(S209).

On the other hand, if it is not determined in the determination processof step S205 that the gravitational acceleration component is in theopposite direction to the predetermined direction (NO) or if thedetermination process of step S205 is not performed, the statedetermination unit 510 waits for the lapse of a predetermined time inthe state in which the direction of a gravitational accelerationcomponent does not correspond to the predetermined direction (S207). Ifthe predetermined time elapses (YES), the state determination unit 510determines that the display unit 110 is in the second state (S209). Onthe other hand, if the direction of a gravitational accelerationcomponent corresponds to the predetermined direction before the lapse ofthe predetermined time, the process returns to step S201.

The process described above makes it possible to determine the state ofthe display unit 110 and to prevent erroneous detection of the secondstate in the case where the user's head inclines for a moment, on thebasis of the detection value obtained by the acceleration sensorincluded in the display unit 110. In the determination process of stepS205 performed selectively, when the direction of the gravitationalacceleration component contained in the acceleration is substantiallyreversed, that is, when the attitude of the display unit 110 is theattitude shown in the portion (c) of FIG. 5, the determination that thedisplay unit 110 is in unusable state without necessity of waiting forthe lapse of a predetermined time makes it possible to determine thestate more quickly. As another example, even when the direction of thegravitational acceleration component contained in the acceleration issubstantially reversed, the state determination unit 510 may determinethe state after waiting for the lapse of a predetermined time.

(2) State Determination Using Acceleration Variation

The human body's acceleration varies depending on individual body partsof human. The user's head on which the display unit 110 is mounted isnot a body part upon which a relatively large value of acceleration isacting like hands and feet. However, the head is undoubtedly one of thebody parts, and thus it keeps moving slightly unless the user holds hishead still with the intention of the user. Thus, the acceleration of thedisplay unit 110 keeps changing to a greater or lesser extent while thedisplay unit 110 is mounted on the user's head. When the user is walkingor running while wearing the display unit 110, the acceleration changessignificantly.

The state determination unit 510 is capable of determining the state ofthe display unit 110 by using the characteristics as described above. Asone example, when a state in which the acceleration variation of thedisplay unit 110 is less than a threshold (a first threshold) iscontinued for a predetermined time, the state determination unit 510 maydetect the second state in which the display unit 110 is worn or carriedby the user in unusable state. As one example, the first threshold is avalue less than the acceleration variation that may occur naturallywhile the display unit 110 is mounted on the user's head, and may be avalue close to zero. Thus, for example, the display unit 110 may becarried by the user while being placed in a bag of the user. In thiscase, if the amount of movement of the user, the user's bag, or the likeis small, then the second state is detected.

Furthermore, the state determination unit 510 may detect the secondstate on condition that the variation exceeding a second thresholdlarger than the first threshold is detected prior to the state in whichthe acceleration variation is less than the first threshold, which iscontinued for a scheduled time time. As one example, the secondthreshold is a value corresponding to the acceleration variation thatoccurs when the display unit 110 is removed from the user's head andthen is placed in a bag or the like, that is, a value corresponding tothe acceleration variation when an impact is applied to the display unit110 (as one example, approximately three times the acceleration ofgravity). In this case, as one example, when the user intentionallyholds his head still while wearing the display unit 110, it is possibleto prevent erroneous detection of the second state.

FIG. 7 is a flowchart showing an example of a process in the case wherethe state determination unit 510 performs the determination based onacceleration variation. Referring to FIG. 7, the state determinationunit 510 acquires acceleration variation (S301). In this connection, theacceleration variation may be acquired by an acceleration sensorincluded in the motion sensor 116 provided in the display unit 110. Inthis example, in determining the state on the basis of the accelerationvariation, the direction of acceleration does not matter, and thus theacceleration sensor is not necessarily a three-axis acceleration sensor.

Then, the state determination unit 510 determines whether theacceleration variation exceeds the second threshold (S303). As describedabove, the second threshold corresponds to the acceleration variationwhen an impact is applied to the display unit 110. Thus, it may beconsidered that step S303 determines whether an impact is applied to thedisplay unit 110. If the acceleration variation exceeds the secondthreshold (YES), the state determination unit 510 determines whether theacceleration variation is less than the first threshold (S305). On theother hand, if the acceleration variation does not exceed the secondthreshold in step S303 (NO), the state determination unit 510 acquiresacceleration variation again.

If it is determined in the determination of step S305 that theacceleration variation is less than the first threshold (YES), the statedetermination unit 510 waits for the lapse of a predetermined time inthe state in which the acceleration variation is less than the firstthreshold (S307). If the predetermined time elapses (YES), the statedetermination unit 510 detects the fact that the display unit 110 is inthe second state (S309). On the other hand, if the accelerationvariation exceeds the first threshold before the predetermined timeelapses, the process returns to step S301.

The process described above makes it possible to determine the statedepending on the acceleration variation of the display unit 110 and toprevent erroneous detection of the second state in the case where theuser intentionally holds his head still.

In the present embodiment, any one of the determination using theacceleration detection value described above and the determination usingthe acceleration variation may be performed, or a combination of bothmay be performed. In the combination of both determination processes, ifthe second state (state in which the display unit 110 is worn or carriedby the user in unusable state) is determined using at least one of theacceleration detection value and the acceleration variation, the statedetermination unit 510 may determine that the display unit 110 is in thesecond state. As one example, when the display unit 110 is carried in abag or the like while maintaining its attitude shown in the portion (a)of FIG. 5, it is difficult to detect the second state on the basis ofthe acceleration detection value. As one example, when the display unit110 is hung around the user's neck or is raised and worn on theforehead, a change in acceleration occurs but the display unit 110 maybe not mounted in proper attitude. In this case, it is difficult todetect the second state on the basis of the acceleration variation. Thedetermination using the combination state of the acceleration detectionvalue and the acceleration variation makes it possible to detect thestate appropriately even in such a case.

(Power Supply State Control)

A power supply control that is performed by the power supply controller520 will be described. In the present embodiment, the power supplycontroller 520 control a power supply state of the display unit 110 anda power supply state of the entire HMD 100 including the display unit110 and the control unit 160, on the basis of a determination resultobtained by determination of the state of the display unit 110 by thestate determination unit 510.

More specifically, in the present embodiment, when the statedetermination unit 510 detects the second state, the power supplycontroller 520 performs a state transition from the power supply stateof the display unit 110 or the HMD 100 (the display unit 110 and thecontrol unit 160) to a power saving state. The power saving state refersto a power supply state in which the power consumption is lower than anormal state. As one example, the display unit 110 can be set to thepower saving state by stopping emission of image display light from thelight source 112, lowering the brightness or resolution of the imagedisplay light, stopping some or all of operations of the motion sensor116, extending an interval of the image capturing performed by thecamera 18, or stopping the image capturing. In addition, the controlunit 160 can be set to the power saving state by changing the operationmode of the processor 162, the communication device 166, the touchsensor 170, the acceleration sensor 176, or the like, or causing thesecomponents to shut down. An example of the power saving state includes astate in which the HMD 100 is powered off.

An example of the power saving state to be set by the power supplycontroller 520 may include a plurality of power saving states in whichtheir individual power consumption is different. As one example, thepower supply controller 520 sets a first power saving state. In thefirst power saving state, in the display unit 110, the emission of imagedisplay light by the light source 112 is stopped, a gyro sensor otherthan the acceleration sensor included in the motion sensor 116 isdeactivated, and the image capturing by the camera 118 is stopped. Inaddition, in the first power saving state, the power supply controller520 may be capable of returning the state of the display unit 110 (orHMD 100) from the power saving state to the normal power supply stateupon the detection of the first state (state in which the display unit110 is worn by the user in usable state) on the basis of theacceleration detection value or the acceleration variation of theacceleration sensor included in the motion sensor 116, withoutdeactivating the processor 162 of the control unit 160.

As one example, the power supply controller 520 sets a second powersaving state. In the second power saving state, in the display unit 110,substantially all of the components including the acceleration sensorare deactivated. Furthermore, in the second power saving state, in thecontrol unit 160, the operation (clock) of the processor 162 is stopped,and the touch sensor 170 and the acceleration sensor 176 aredeactivated. On the other hand, in this case, the communication device166 is set to a predetermined standby mode, which will be describedlater.

FIG. 8 illustrates an example of a method of returning the state of theprocessor 162 in which the clock is stopped in the second power savingstate. In the example shown in FIG. 8, a Bluetooth (registeredtrademark) module (BT module) 166 a and a Wi-Fi module 166 b areprovided as the communication device 166. In the case where the clock ofthe processor 162 is stopped in the second power saving state, theprocessor 162 resumes its operation by regarding, as an interruptfactor, the reception of a key input signal from the input key 168, thereception of a signal by the BT module 166 a from other devicesincluding the smartphone 200, and the reception of a signal by the Wi-Fimodule 166 b from other devices including the smartphone 200. In the BTmodule 166 a, as one example, the sniff mode is set as the standby mode.In addition, in the Wi-Fi module 166 b, as one example, thewake-on-wireless (WOW) mode is set as the standby mode. In the casewhere such a mode is set, the processor 162, when receiving a signalfrom the smartphone 200 or the like, is capable of resuming itsoperation relatively quickly. When the processor 162 resumes itsoperation due to the interrupt factors described above, the power supplycontroller 520 causes the HMD 100 to undergo a transition to its normalpower supply state.

The power supply controller 520 may use the first power saving state andthe second power saving state, for example, depending on the duration ofthe second state (the state in which the display unit 110 is worn orcarried by the user in unusable state) that is detected by the statedetermination unit 510. More specifically, the state determination unit510 may cause the power supply state of the HMD 100 to undergo astepwise transition from the first power saving state to the secondpower saving state (power saving state having lower power consumption)depending on the duration of the second state.

As one example, when the state determination unit 510 detects the secondstate, the power supply controller 520 causes the power supply state ofthe HMD 100 to undergo a transition from its normal state to the firstpower saving state. In the first power saving state, the statedetermination unit 510 is still capable of determining the state of thedisplay unit 110. Thus, in the first power saving state, when the statedetermination unit 510 no longer detects the second state or detects thefirst state (the state in which the display unit 110 is worn by the userin usable state), the power supply controller 520 is capable of causingthe power state to return from the power saving state to the normalstate.

Furthermore, when the second state continues for a predetermined time ormore, the power supply controller 520 causes the power supply state ofthe HMD 100 to undergo a transition from the first power saving state tothe second power saving state. In the second power saving state, thestate determination unit 510 no longer detects the state, and thus thepower supply state does not return from the power saving state, forexample even if the acceleration of the display unit 110 satisfies thedetermination condition of the first state. However, in the second powersaving state, in addition to the state in which the processor 162 can beactivated when a key input signal is received through the input key 168,the state in which the communication device 166 can resume its operationrelatively quickly when a signal from the smartphone 200 or the like isreceived remains. Thus, even in the second power saving state, the powersupply state of the HMD 100 is allowed to return from the power savingstate in a time that is shorter than the state in which the HMD 100 ispowered off.

As described above, in the present embodiment, the power supply state ofthe display unit 100 or the power supply state of the HMD 100 includingthe display unit 110 is controlled on the basis of the determinationresult obtained by determining the state of the attitude or movement ofthe display unit 110, which is indicated by the detection value obtainedby the acceleration sensor included in the motion sensor 116. Thecontrol of the power supply state specifically includes the transitionto the power saving state. Thus, the control of the power supply statebased on the state of the display unit 110 makes it possible to reducepower consumption without compromising the user's convenience by causingthe function of the display unit 110 or the HMD 100 to be stopped whilethe user does not wear the display unit 110 in usable state.

In the present embodiment, the state of the display unit 110 isdetermined on the basis of the acceleration detection value or theacceleration variation. Thus, for example, as the first power savingstate described above, it is possible to detect continuously whether itis mounted even in the state in which some functions of the HMD 100 arestopped. The power consumption of the acceleration sensor included inthe motion sensor 116 of the display unit 110 is typically lower thanthat of the light source 112, the gyro sensor included in the motionsensor 116, or the like. Thus, when the light source 112, the gyrosensor, or the like is caused to be stopped, the effect of the reductionof power consumption can be obtained even if the acceleration sensormaintains its operation.

2. Second Embodiment

A second embodiment of the present disclosure will be described. In thesecond embodiment, the state of the display unit 110 is determined usinga method that is different from the first embodiment in a system 10similar to the first embodiment. Thus, for the configuration of thesystem that is common to the first embodiment, repeated description willbe omitted, and in particular, a process for the state determinationwill be described.

FIG. 9 is a schematic block diagram showing a functional configurationof the system according to the second embodiment of the presentdisclosure. Referring to FIG. 9, in a system 20 according to the presentembodiment, a display unit 110 of an HMD 100 is provided with a switch120 that is configured to detect the state of a connection part of anattachment member, in addition to functional components similar to thesystem 10 described above. This switch 120 will be described below withreference to FIG. 10.

FIG. 10 is a diagram showing an example of the switch used to detect thestate of the attachment member in the present embodiment. In the exampleshown in FIG. 10, the display unit 110 is configured to include a temple122 and a hinge 124. The hinge 124 is provided between a portionincluding the light guide plate 114 and the temple 122. The display unit110 is an example of the wearable optical device in the presentembodiment, the temple 122 is an example of the attachment member usedto attach the wearable optical device to the user's head, and the hinge124 is an example of the connection part of the attachment member. Thetemple 122 and the hinge 124 are well known as components of eyeglasses,and thus a detailed description will be omitted.

In the illustrated example, the rotation about the axis of the hinge 124allows the temple 122 to be folded. In this connection, the switch 120is provided at a portion of the hinge 124, and outputs a signal when thetemple 122 is folded (deformed) by the rotation of the hinge 124 asshown in the example of FIG. 10.

FIG. 11 is a block diagram showing a functional configuration used forcontrolling power supply of the HMD in the second embodiment of thepresent disclosure. Referring to FIG. 11, in the present embodiment, thepower supply control of the HMD is implemented by the functionalcomponents including a state determination unit 610 and the power supplycontroller 520. These functional components are implemented, forexample, by any of the processor 162 included in the control unit 160 ofthe HMD 100, the processor 202 of the smartphone 200, and the processor302 of the server 300, or implemented in cooperation between them, whichis similar to the first embodiment.

Also in the present embodiment, the state determination unit 610determines that the state of the display unit 110 is at least one of thefirst state of being worn by the user in usable state and the secondstate of being worn or carried by the user in unusable state. Morespecifically, in the present embodiment, the switch 120 is an example ofa state detection unit configured to detect the state of the attachmentmember of the display unit 110.

As described above, in the present embodiment, the attachment member isthe temple 122. The switch 120 provided in the hinge 124 (connectionpart) acquires information indicating the state of the temple 122. Thestate determination unit 610, when acquiring a signal output from theswitch 120 in the case where the temple 122 is folded by the rotation ofthe hinge 124, determines that the display unit 110 is in the secondstate (the state in which the display unit 110 is worn or carried by theuser in unusable state). Alternatively, the state determination unit610, when acquiring a signal output from the switch 120 in the casewhere the temple 122 is extended by the rotation of the hinge 124, maydetermine that the display unit 110 is in the first state (the state inwhich the display unit 110 is worn by the user in usable state).

The power supply control performed by the power supply controller 520 isperformed in a way similar to the first embodiment, and thus a detaileddescription will be omitted. When the state determination unit 610detects the second state on the basis of the signal output from theswitch 120 in the case where the temple 122 of the display unit 110 isfolded, the power supply controller 520 allows the power supply state ofthe display unit 110 or the HMD 100 to undergo a transition to the powersaving state. In this connection, as one example, the power supplycontroller 520 defines the first power saving state in which the statedetermination unit 610 is capable of determining the state based on thesignal from the switch 120 and the second power saving state in whichthe determination of the state is not performed instead of furtherreducing the power consumption. After the power supply state undergoes atransition to the first power saving state, when the second state (thestate indicating that the temple 122 is folded by the signal from theswitch) continues for a predetermined time or more, the power supplycontroller 520 may cause the power supply state to undergo a transitionto the second power saving state.

(Modification)

FIG. 12 is a diagram showing an example of the switch configured todetect the state of the attachment member in the modification of thepresent embodiment. In the example shown in FIG. 12, the display unit110 is configured to include a belt 126 and a buckle 128. The belt 126is wounded around the user's head to secure the display unit 110 to thehead. Thus, the belt 126 is an example of the attachment member of thewearable optical device in the present modification, and the buckle 128is an example of the connection part of the attachment member. The belt126 is flexible and elastic, as one example. Thus, when the buckle 128is fastened, a ring having the inner diameter that is suitable forsecuring the display unit 110 to the user's head with the belt 126 andthe portion included in the light guide plate 114 is maintained, whilewhen the buckle 128 is unfastened, the belt 126 is deformed and the ringis opened, thereby facilitating detachment of the display unit 110.

In the present modification, the switch 120 is provided at a portion ofthe buckle 128 and outputs a signal when the buckle 128 is unfastened asshown in the portions (a) and (b) of FIG. 12. The state determinationunit 610, when acquiring this signal, determines that the display unit110 is in the second state (the state in which the display unit 110 isworn or carried by the user in unusable state). Alternatively, when thebuckle 128 is fastened, the switch outputs a signal. The statedetermination unit 610, when acquiring this signal, may determine thatthe display unit 110 is in the first state (the state in which thedisplay unit 110 is worn by the user in usable state).

As described above, in the present embodiment, the state of the displayunit 110 is determined on the basis of the information indicating thestate of the attachment member of the display unit 110 (a physical stateof the wearable optical device). The power supply state of the displayunit 110 or the HMD 100 including the display unit 110 is controlled onthe basis of a determination result obtained by the determination. Thecontrol of the power supply state based on the state of the display unit110 makes it possible to reduce power consumption without compromisingthe user's convenience by causing the function of the HMD 100 to bestopped while the user does not wear the display unit 110 in usablestate.

Although the example in which the attachment member has the connectionpart and the state detection unit detects the state of the connectionpart has been described in the present embodiment, the attachment membermay not necessarily include the connection part in another embodiment.As one example, the wearable optical device may be mounted on the user'shead by inserting a body part on the user's head or face into theattachment member that is elastically deformable. In this case, thestate detection unit may be configured to include a strain gauge used todetect the state in which the attachment member is elastically deformedand to determine that the state in which the attachment member iselastically deformed is the second state. When the attachment memberincludes the connection part, examples of the state detection unit usedto detect the state of the connection part include, but not limited to amechanical switch, an electrical switch provided with a conductivepattern and a contact and an optical switch provided with a reflectivephotodetector.

The state determination using the state of the attachment member in thepresent embodiment may be combined with the state determination based onthe acceleration detection value and/or acceleration variation in thefirst embodiment. When the temple 122 is folded or the buckle 128 isunfastened irrespective of the attitude or movement of the display unit110, the display unit 110 is more likely to be in the unusable state. Onthe other hand, when the temple 122 is extended or the buckle 128 isfastened, the display unit 110 may be housed or may be hung around theuser's neck. The combination between the state determination using thestate of the attachment member and the state determination based on theacceleration detection value or acceleration variation makes it possibleto detect the state of the display unit 110 properly even in the abovecase.

3. Third Embodiment

A third embodiment of the present disclosure will be described. In thethird embodiment, the state of the display unit 110 is determined usinga method that is different from the first embodiment in a system 10similar to the first embodiment. Thus, for the configuration of thesystem that is common to the first embodiment, repeated description willbe omitted, and in particular, a process for the state determinationwill be described.

FIG. 13 is a schematic block diagram showing a functional configurationof the system according to the third embodiment of the presentdisclosure. Referring to FIG. 13, in a system 30 according to thepresent embodiment, a display unit 110 of an HMD 100 is provided with anilluminance sensor 130, in addition to functional components similar tothe system 10 (or system 20) described above. The illuminance sensor 130is an example of a state detection unit used to detect an environmentalcondition surrounding the wearable optical device and detects theilluminance surrounding the display unit 110.

FIG. 14 is a block diagram showing a functional configuration used forcontrolling power supply of the HMD in the third embodiment of thepresent disclosure. Referring to FIG. 14, in the present embodiment, thepower supply control of the HMD is implemented by functional componentsincluding a state determination unit 710 and the power supply controller520. These functional components are implemented, for example, by any ofthe processor 162 included in the control unit 160 of the HMD 100, theprocessor 202 of the smartphone 200, and the processor 302 of the server300, or implemented in cooperation between them, which is similar to thefirst embodiment.

Also in the present embodiment, the state determination unit 710determines that the state of the display unit 110, which is detected bythe state detection unit, is at least one of the first state of beingworn by the user in usable state and the second state of being worn orcarried by the user in unusable state. More specifically, in the presentembodiment, the state determination unit 710 detects the second state(the state in which the display unit 110 is worn or carried by the userin unusable state) when a predetermined time elapses in a state in whichthe illuminance detected by the illuminance sensor 130 included in thedisplay unit 110 is less than a threshold. Alternatively, the statedetermination unit 710 may detect the first state (the state in whichthe display unit 110 is worn by the user in usable state) when apredetermined time elapses in a state in which the illuminance detectedby the illuminance sensor 130 included in the display unit 110 exceeds athreshold.

The power supply control performed by the power supply controller 520 isperformed in a way similar to the first embodiment, and thus a detaileddescription will be omitted. As one example, when a predetermined timeelapses in a state in which the illuminance detected by the illuminancesensor 130 included in the display unit 110 is less than a threshold,the power supply controller 520 causes the power supply state of thedisplay unit 110 or the HMD 100 to undergo a transition to the powersaving state. In this connection, as one example, the power supplycontroller 520 defines the first power saving state in which the statedetermination unit 710 is capable of determining the state based on thedetection value obtained by the illuminance sensor 130 and the secondpower saving state in which the determination of the state is notperformed instead of further reducing the power consumption. After thepower supply state undergoes a transition to the first power savingstate, when the second state (the state in which the detection valueobtained by the illuminance sensor 130 is less than a threshold)continues for a predetermined time or more, the power supply controller520 may cause the power supply state to undergo a transition to thesecond power saving state.

As one example, when the display unit 110 is housed in a casing, if thecasing is closed, the illuminance surrounding the display unit 110becomes substantially zero. When the display unit 110 is housed in acasing, the display unit 110 is carried by the user in unusable state.Thus, the state determination unit 710 is capable of determining thatthe display unit 110 is in the second state on condition that apredetermined time elapses in a state in which the illuminance detectedby the illuminance sensor 130 is less than a threshold that is close tozero. The casing is not limited to one in which the entire HMD 100 iscompletely housed, but the casing may be a cover or the like in whichonly the display unit 110 is housed.

As described above, in the present embodiment, the power supply state ofthe display unit 110 or the HMD 100 including the display unit 110 iscontrolled on the basis of the illuminance surrounding the display unit110 (an environmental condition surrounding the wearable opticaldevice), which is detected by the illuminance sensor 130 (the statedetection unit). The control of the power supply state based on thestate of the display unit 110 makes it possible to reduce powerconsumption without compromising the user's convenience by causing thefunction of the HMD 100 to be stopped while the user does not wear thedisplay unit 110 in usable state.

The state determination using the detection value obtained by theilluminance sensor 130 in the present embodiment, the statedetermination based on the acceleration detection value or accelerationvariation in the first embodiment, and/or the state determination usingthe signal from the switch 120 in the second embodiment may be combinedwith each other. The respective state determination processes areperformed in individual different conditions, and thus it is possible toimprove the accuracy of the state determination by such combination.

FIG. 15 is a flowchart showing an example of a process performed bycombining the attachment state detection in the first, second, and thirdembodiments. Referring to FIG. 15, the state determination unit 710determines the state of the display unit 110 on the basis of the signalfrom the switch 120 used to detect the state of the attachment member ofthe display unit 110 (S401). If it is determined that the display unit110 is in the second state (YES in S403), the power supply controller520 causes the power supply state of the display unit 110 or the HMD 100to undergo a transition to the power saving state (S405).

On the other hand, if it is not determined in step S403 to be in thesecond state, the state determination unit 710 determines the state ofthe display unit 110 on the basis of the detection value obtained by theilluminance sensor 130 used to detect the illuminance surrounding thedisplay unit 110 (S407). If it is determined to be in the second state(YES in step S409), the power supply controller 520 causes the powersupply state of the display unit 110 or the HMD 100 to undergo atransition to the power saving state (S405).

If it is not determined in step S409 to be in the second state, thestate determination unit 710 determines the state of the display unit110 on the basis of the detection value or variation obtained by theacceleration sensor that detects the acceleration of the display unit110 (S411). If it is determined that the display unit 110 is in thesecond state (YES in S413), the power supply controller 520 causes thepower supply state of the display unit 110 or the HMD 100 to undergo atransition to the power saving state (S405). In the determinationprocesses described above, if it is determined to be in the secondstate, the power supply controller 520 does not change the power supplystate and the process returns to step S401.

When the state determination processes described in the first to thirdembodiments are combined as in the above example, the determinationusing the detection value obtained by the switch 120 or the illuminancesensor 130 has certainty higher than other state determination processes(if the condition is satisfied, the display unit 110 is more likely tobe in unusable state), and thus the detection process for this statedetermination is first performed. Then, if it is determined that thedisplay unit 110 is in the second state, the power supply state mayundergo a transition to the power saving state without performing thedetermination based on the acceleration.

(4. Other Examples)

As another example, in an embodiment of the present disclosure, examplesof the state detection unit used to detect the state of the wearableoptical device are not limited to the examples described above, but itmay be implemented using various sensors, switches, or the like. Some ofthe other examples will be described by taking a system 10 similar tothe first embodiment as an example.

As one example, the state detection unit may detect the state of theuser of the wearable optical device. For the system 10, a line-of-sightsensor included in the display unit 110 of the HMD 100 functions as thestate detection unit. The line-of-sight sensor detects the line of sightof the user who wears the display unit 110. In this case, the statedetermination unit determines the state in which the line-of-sightsensor does not detect the line of sight of the user is the second statein which the display unit 110 is worn or carried by the user in unusablestate.

The state detection unit, when detecting the state of the user, maydetect an index indicating a fact that the display unit 110 is incontact with or in proximity to the user's body such as body temperatureand pulse, but not limited to the line of sight. As with the line ofsight, even when the body temperature and pulse are detected, a state inwhich these targets are not detected is determined to be the secondstate in which the display unit 110 is worn or carried by the user inunusable state.

(5. Hardware Configuration)

Next, a hardware configuration of an electronic apparatus according toan embodiment of the present disclosure will be described with referenceto FIG. 16. FIG. 16 is a block diagram showing an example of thehardware configuration of the electronic apparatus according to theembodiment of the present disclosure. The illustrated electronicapparatus 900 can realize, for example, the HMD 100, the smartphone 200,and/or the server devices constituting the server 300 of theabove-described embodiments.

The electronic apparatus 900 includes a CPU (Central Processing Unit)901, a ROM (Read Only Memory) 903, and a RAM (Random Access Memory) 905.In addition, the electronic apparatus 900 may include a host bus 907, abridge 909, an external bus 911, an interface 913, an input device 915,an output device 917, a storage device 919, a drive 921, a connectionport 923, and a communication device 925. Further, the electronicapparatus 900 may include an imaging device 933 and a sensor 935 asnecessary. The electronic apparatus 900 may include a processing circuitsuch as a DSP (Digital Signal Processor) or ASIC (Application SpecificIntegrated Circuit), alternatively or in addition to the CPU 901.

The CPU 901 serves as an operation processor and a controller, andcontrols all or some operations in the electronic apparatus 900 inaccordance with various programs recorded in the ROM 903, the RAM 905,the storage device 919 or a removable recording medium 927. The ROM 903stores programs and operation parameters which are used by the CPU 901.The RAM 905 temporarily stores program which are used in the executionof the CPU 901 and parameters which are appropriately modified in theexecution. The CPU 901, ROM 903, and RAM 905 are connected to each otherby the host bus 907 configured to include an internal bus such as a CPUbus. In addition, the host bus 907 is connected to the external bus 911such as a PCI (Peripheral Component Interconnect/Interface) bus via thebridge 909.

The input device 915 is a device which is operated by a user, such as amouse, a keyboard, a touch panel, buttons, switches and a lever. Theinput device 915 may be, for example, a remote control unit usinginfrared light or other radio waves, or may be an external connectiondevice 929 such as a portable phone operable in response to theoperation of the electronic apparatus 900. Furthermore, the input device915 includes an input control circuit which generates an input signal onthe basis of the information which is input by a user and outputs theinput signal to the CPU 901. By operating the input device 915, a usercan input various types of data to the electronic apparatus 900 or issueinstructions for causing the electronic apparatus 900 to perform aprocessing operation.

The output device 917 includes a device capable of visually or audiblynotifying the user of acquired information. The output device 917 mayinclude a display device such as an LCD (Liquid Crystal Display), a PDP(Plasma Display Panel), and an organic EL (Electro-Luminescence)displays, an audio output device such as a speaker or a headphone, and aperipheral device such as a printer. The output device 917 may outputthe results obtained from the process of the electronic apparatus 900 ina form of a video such as text or an image, and an audio such as voiceor sound.

The storage device 919 is a device for data storage which is configuredas an example of a storage unit of the electronic apparatus 900. Thestorage device 919 includes, for example, a magnetic storage device suchas a HDD (Hard Disk Drive), a semiconductor storage device, an opticalstorage device, or a magneto-optical storage device. The storage device919 stores programs to be executed by the CPU 901, various data, anddata obtained from the outside.

The drive 921 is a reader/writer for the removable recording medium 927such as a magnetic disk, an optical disk, a magneto-optical disk, or asemiconductor memory, and is embedded in the electronic apparatus 900 orattached externally thereto. The drive 921 reads information recorded inthe removable recording medium 927 attached thereto, and outputs theread information to the RAM 905. Further, the drive 921 writes in theremovable recording medium 927 attached thereto.

The connection port 923 is a port used to directly connect devices tothe electronic apparatus 900. The connection port 923 may include a USB(Universal Serial Bus) port, an IEEE1394 port, and a SCSI (SmallComputer System Interface) port. The connection port 923 may furtherinclude an RS-232C port, an optical audio terminal, an HDMI (registeredtrademark) (High-Definition Multimedia Interface) port, and so on. Theconnection of the external connection device 929 to the connection port923 makes it possible to exchange various data between the electronicapparatus 900 and the external connection device 929.

The communication device 925 is, for example, a communication interfaceincluding a communication device or the like for connection to acommunication network 931. The communication device 925 may be, forexample, a communication card for a wired or wireless LAN (Local AreaNetwork), Bluetooth (registered trademark), WUSB (Wireless USB) or thelike. In addition, the communication device 925 may be a router foroptical communication, a router for ADSL (Asymmetric Digital SubscriberLine), a modem for various kinds of communications, or the like. Thecommunication device 925 can transmit and receive signals to and from,for example, the Internet or other communication devices based on apredetermined protocol such as TCP/IP. In addition, the communicationnetwork 931 connected to the communication device 925 may be a networkor the like connected in a wired or wireless manner, and may be, forexample, the Internet, a home LAN, infrared communication, radio wavecommunication, satellite communication, or the like.

The imaging device 933 is a device that generates an image by imaging areal space using an image sensor such as a charge-coupled device (CCD)or a complementary metal-oxide-semiconductor (CMOS) sensor, as well asvarious members such as one or more lenses for controlling the formationof a subject image on the image sensor, for example. The imaging device933 may be a device that takes still images, and may also be a devicethat takes moving images.

The sensor 935 is any of various sensors such as an acceleration sensor,a gyro sensor, a geomagnetic sensor, an optical sensor, or a soundsensor, for example. The sensor 935 acquires information regarding thestate of the electronic apparatus 900, such as the orientation of thecase of the electronic apparatus 900, as well as information regardingthe environment surrounding the electronic apparatus 900, such as thebrightness or noise surrounding the electronic apparatus 900, forexample. The sensor 935 may also include a Global Positioning System(GPS) sensor that receives GPS signals and measures the latitude,longitude, and altitude of the apparatus.

The foregoing thus illustrates an exemplary hardware configuration ofthe electronic apparatus 900. Each of the above components may berealized using general-purpose members, but may also be realized inhardware specialized in the function of each component. Such aconfiguration may also be modified as appropriate according to thetechnological level at the time of the implementation.

(6. Supplement)

The embodiments of the present disclosure may include the electronicapparatus, the system, the method executed in the electronic apparatusor the system, the program for causing the electronic apparatus tofunction, and the non-transitory tangible media having the programrecorded thereon, which have been described above, for example.

The preferred embodiment(s) of the present disclosure has/have beendescribed above with reference to the accompanying drawings, whilst thepresent disclosure is not limited to the above examples. A personskilled in the art may find various alterations and modifications withinthe scope of the appended claims, and it should be understood that theywill naturally come under the technical scope of the present disclosure.

The effects described in the specification are just explanatory orexemplary effects, and are not limiting. That is, the technologyaccording to the present disclosure can exhibit other effects that areapparent to a person skilled in the art from the descriptions in thespecification, along with the above effects or instead of the aboveeffects.

Additionally, the present technology may also be configured as below.

-   (1)

An electronic apparatus including:

a wearable optical device;

a state detection unit configured to detect a state relating to thewearable optical device;

a state determination unit configured to determine that the detectedstate is at least one of a first state in which the wearable opticaldevice is worn by a user in usable state or a second state in which thewearable optical device is worn or carried by the user in unusablestate; and

a power supply controller configured to control a power supply state ofthe electronic apparatus based on a result obtained by thedetermination.

-   (2)

The electronic apparatus according to (1),

wherein the state detection unit detects a state of an attitude ormovement of the wearable optical device.

-   (3)

The electronic apparatus according to (2),

wherein the state detection unit includes an acceleration sensor.

-   (4)

The electronic apparatus according to (3),

wherein the state determination unit executes the determination based ona detection value obtained by the acceleration sensor.

-   (5)

The electronic apparatus according to (4),

wherein the state determination unit determines that the detected stateis the second state when a direction of a gravitational accelerationcomponent detected by the acceleration sensor is different from apredetermined direction.

-   (6)

The electronic apparatus according to (5),

wherein the state determination unit determines that the detected stateis the second state when a state in which the direction of thegravitational acceleration component is different from a predetermineddirection continues for a predetermined time.

-   (7)

The electronic apparatus according to any one of (3) to (6),

wherein the state determination unit executes the determination based ona variation in detection values obtained by the acceleration sensor.

-   (8)

The electronic apparatus according to (7),

wherein the state determination unit determines that the detected stateis the second state when a state in which the variation is less than afirst threshold continues for a predetermined time.

-   (9)

The electronic apparatus according to any one of (1) to (8),

wherein the wearable optical device includes an attachment member usedfor attachment to a head of the user, and

wherein the state detection unit detects a state of the attachmentmember.

-   (10)

The electronic apparatus according to (9),

wherein the attachment member includes a connection part,

wherein the state detection unit detects a state of the connection part,and

wherein the state determination unit executes the determination based onthe state of the connection part.

-   (11)

The electronic apparatus according to (9),

wherein the attachment member is elastically deformable,

wherein the state detection unit detects a state in which the attachmentmember is elastically deformed, and

wherein the state determination unit determines that the state in whichthe attachment member is elastically deformed is the second state.

-   (12)

The electronic apparatus according to any one of (1) to (11),

wherein the state detection unit detects a state of the user.

-   (13)

The electronic apparatus according to (12),

wherein the state detection unit includes a line-of-sight sensorconfigured to detect a line of sight of the user, and

wherein the state determination unit determines that a state in whichthe line-of-sight sensor is not detecting the line of sight of the useris the second state.

-   (14)

The electronic apparatus according to any one of (1) to (13),

wherein the state detection unit detects an environmental conditionsurrounding the wearable optical device.

-   (15)

The electronic apparatus according to (14),

wherein the state detection unit detects illuminance surrounding thewearable optical device, and

wherein the state determination unit determines that a state in whichthe illuminance is less than a threshold is the second state.

-   (16)

The electronic apparatus according to any one of (1) to (15),

wherein the power supply controller causes the power supply state toundergo a transition to a power saving state when the detected state isdetermined to be the second state.

-   (17)

The electronic apparatus according to (16),

wherein the power saving state includes a plurality of power savingstates each having different power consumption, and

wherein the power supply controller causes the power supply state toundergo a stepwise transition to the power saving state having lowerpower consumption depending on a duration of the second state.

-   (18)

The electronic apparatus according to (16) or (17),

wherein the power supply controller causes the power supply state toreturn from the power saving state when the first state is determined.

-   (19)

The electronic apparatus according to (18),

wherein the power saving state includes a first power saving state inwhich the state detection unit is capable of detecting a statecorresponding to the first state or the second state and a second powersaving state in which the state detection unit is incapable of detectingthe first state or the second state, the second power saving state beinglower in power consumption than the first power saving state, and

wherein the power supply controller causes the power supply state toundergo a stepwise transition from the first power saving state to thesecond power saving state depending on a duration of the second stateand causes the power supply state to return from the power saving statewhen a state detected in the first power saving state is determined tobe the first state.

-   (20)

A method of controlling power supply including:

detecting a state relating to a wearable optical device;

determining that the detected state is at least one of a first state inwhich the wearable optical device is worn by a user in usable state or asecond state in which the wearable optical device is worn or carried bythe user in unusable state; and

controlling a power supply state of an electronic apparatus includingthe wearable optical device based on a result obtained by thedetermination.

REFERENCE SIGNS LIST

-   10 system-   100 HMD-   110 display unit-   112 light source-   114 light guide plate-   116 motion sensor-   118 camera-   120 switch-   122 temple-   124 hinge-   126 belt-   128 buckle-   130 illuminance sensor-   160 control unit-   162 processor-   164 memory-   200 smartphone-   202 processor-   204 memory-   300 server-   302 processor-   304 memory-   510, 610, 710 state determination unit-   520 power supply controller

1. An electronic apparatus comprising: a wearable optical device; astate detection unit configured to detect a state relating to thewearable optical device; a state determination unit configured todetermine that the detected state is at least one of a first state inwhich the wearable optical device is worn by a user in usable state or asecond state in which the wearable optical device is worn or carried bythe user in unusable state; and a power supply controller configured tocontrol a power supply state of the electronic apparatus based on aresult obtained by the determination.
 2. The electronic apparatusaccording to claim 1, wherein the state detection unit detects a stateof an attitude or movement of the wearable optical device.
 3. Theelectronic apparatus according to claim 2, wherein the state detectionunit includes an acceleration sensor.
 4. The electronic apparatusaccording to claim 3, wherein the state determination unit executes thedetermination based on a detection value obtained by the accelerationsensor.
 5. The electronic apparatus according to claim 4, wherein thestate determination unit determines that the detected state is thesecond state when a direction of a gravitational acceleration componentdetected by the acceleration sensor is different from a predetermineddirection.
 6. The electronic apparatus according to claim 5, wherein thestate determination unit determines that the detected state is thesecond state when a state in which the direction of the gravitationalacceleration component is different from a predetermined directioncontinues for a predetermined time.
 7. The electronic apparatusaccording to claim 3, wherein the state determination unit executes thedetermination based on a variation in detection values obtained by theacceleration sensor.
 8. The electronic apparatus according to claim 7,wherein the state determination unit determines that the detected stateis the second state when a state in which the variation is less than afirst threshold continues for a predetermined time.
 9. The electronicapparatus according to claim 1, wherein the wearable optical deviceincludes an attachment member used for attachment to a head of the user,and wherein the state detection unit detects a state of the attachmentmember.
 10. The electronic apparatus according to claim 9, wherein theattachment member includes a connection part, wherein the statedetection unit detects a state of the connection part, and wherein thestate determination unit executes the determination based on the stateof the connection part.
 11. The electronic apparatus according to claim9, wherein the attachment member is elastically deformable, wherein thestate detection unit detects a state in which the attachment member iselastically deformed, and wherein the state determination unitdetermines that the state in which the attachment member is elasticallydeformed is the second state.
 12. The electronic apparatus according toclaim 1, wherein the state detection unit detects a state of the user.13. The electronic apparatus according to claim 12, wherein the statedetection unit includes a line-of-sight sensor configured to detect aline of sight of the user, and wherein the state determination unitdetermines that a state in which the line-of-sight sensor is notdetecting the line of sight of the user is the second state.
 14. Theelectronic apparatus according to claim 1, wherein the state detectionunit detects an environmental condition surrounding the wearable opticaldevice.
 15. The electronic apparatus according to claim 14, wherein thestate detection unit detects illuminance surrounding the wearableoptical device, and wherein the state determination unit determines thata state in which the illuminance is less than a threshold is the secondstate.
 16. The electronic apparatus according to claim 1, wherein thepower supply controller causes the power supply state to undergo atransition to a power saving state when the detected state is determinedto be the second state.
 17. The electronic apparatus according to claim16, wherein the power saving state includes a plurality of power savingstates each having different power consumption, and wherein the powersupply controller causes the power supply state to undergo a stepwisetransition to the power saving state having lower power consumptiondepending on a duration of the second state.
 18. The electronicapparatus according to claim 16, wherein the power supply controllercauses the power supply state to return from the power saving state whenthe first state is determined.
 19. The electronic apparatus according toclaim 18, wherein the power saving state includes a first power savingstate in which the state detection unit is capable of detecting a statecorresponding to the first state or the second state and a second powersaving state in which the state detection unit is incapable of detectingthe first state or the second state, the second power saving state beinglower in power consumption than the first power saving state, andwherein the power supply controller causes the power supply state toundergo a stepwise transition from the first power saving state to thesecond power saving state depending on a duration of the second stateand causes the power supply state to return from the power saving statewhen a state detected in the first power saving state is determined tobe the first state.
 20. A method of controlling power supply comprising:detecting a state relating to a wearable optical device; determiningthat the detected state is at least one of a first state in which thewearable optical device is worn by a user in usable state or a secondstate in which the wearable optical device is worn or carried by theuser in unusable state; and controlling a power supply state of anelectronic apparatus including the wearable optical device based on aresult obtained by the determination.